This application is one of two related applications filed on the same day. The other application Ser. No. 10/026,197 is entitled xe2x80x9cLatently Dispersible Barrier Composite Materialxe2x80x9d with inventors Ann L. McCormack and Richard L. Shick, herein incorporated by reference.
For commode liners it is desired to contain and/or temporarily prevent passage of aqueous waste or other aqueous materials, and at some later time dispose of the barrier material in a clean and environmentally friendly manner. To be effective, the material of the commode liner should temporarily provide a barrier to leakage, and at the appropriate time desirably break up into components that facilitate suitable disposal, especially by flushing down a toilet, while minimizing adverse effects on the environment.
Prior containers using water sensitive layers of, for example, polyvinyl alcohol (PVOH) exist. Difficulties have been identified with these prior containers because many water sensitive materials like PVOH become dimensionally unstable when exposed to conditions of moderate to high humidity and tend to weaken or stretch. In use, for example, the material can stretch out of shape and/or weaken to the point of rupture. Attempts to add stability by increasing the barrier film thickness, for example, add unacceptable cost and/or increase the issues to be addressed upon disposal. Commode liners made of thicker films have a greater tendency to remain intact on flushing, for example, and clog toilets or downstream systems.
The need continues, therefore, for commode liners providing temporary barrier, latently dispersible properties that are stable under use conditions but also easily disposable under aqueous conditions as by flushing, for example. There is also a need to design the shape of the commode liner to maximize its flushability, especially when disposed of in a modern low water usage toilet. The present invention addresses this and similar needs.
The present invention includes commode liners of a unique design that are easily flushed by modern low volume toilets. A commode liner using this design is formed from a first and a second opposing member joined together forming a top including an opening, a bottom, and a pair of opposing sides having a separation distance D. The separation distance D varies from the top to the bottom, and the distance D is larger at the top than at the bottom. Thus, the commode liner is tapered and easily flushed by a toilet.
The present invention is also directed at commode liners formed from latently dispersible barrier composites using a low strength barrier layer of water insoluble composition combined with a water sensitive, low strength carrier and on the opposing side of the carrier an inextensible, dispersible support layer. The layers of the commode liner material are bonded and provide a barrier to aqueous liquid contact from one side but the combination disperses when contacted by aqueous liquid from the other side. In use as a commode liner convenient and environmentally sensitive disposal may be achieved. Examples of barrier layers include films or fine fibers of very lightweight construction using polymers such as polylactic acid or polycaprolactone. Examples of water sensitive carrier webs include films of PVOH with or without other components. Examples of inextensible support materials include higher modulus or low stretch toilet tissue grades.
Where all component layers of the commode liner material are biodegradable and/or dispersible, disposal by flushing is facilitated. For many applications it will be desirable to maintain component layers as light or low basis weight as is compatible with the intended use. In particular, the barrier layer may not be readily dispersible if it is of increased thickness. Cost will provide an incentive to reduce the weight of the component layers, particularly for single use applications. Many commode liner applications will use a barrier layer of polylactic acid (PLA) having a thickness in the range of from about 0.5 to about 2.0 microns, PVOH film carrier layer having a thickness in the range of from about 10 to about 50 microns, and a tissue support layer in the range of from about 10 to about 30 gsm, for example. As a result, the composite for the commode liner will desirably have a hydrohead property of at least about 15 mbar, for some applications at least about 25 mbar, for more demanding applications at least about 50 mbar, and in some cases at least about 75 mbar. Bonding of the layers may be by a variety of means that preserve desired properties, including thermal (such as coextrusion or extrusion coating, for example) and adhesive, pattern and smooth bonding means.
As used herein unless the context requires a different meaning, the following terms have the meanings set forth below:
As used herein and in the claims, the term xe2x80x9ccomprisingxe2x80x9d is inclusive or open-ended and does not exclude additional unrecited elements, compositional components, or method steps.
As used herein the term xe2x80x9cnonwoven fabric or webxe2x80x9d means a web having a structure of individual fibers or threads which are interlaid, but not in an identifiable manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from many processes such as for example, meltblowing processes, spunbonding processes, and bonded carded web processes. The basis weight of nonwoven fabrics is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and the fiber diameters useful are usually expressed in microns. (Note that to convert from osy to gsm, multiply osy by 33.91).
As used herein the term xe2x80x9cmeltblown fibersxe2x80x9d means fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into converging high velocity, usually hot, gas (e.g. air) streams which attenuate the filaments of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly dispersed meltblown fibers. Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to Butin et al. Meltblown fibers are microfibers that may be continuous or discontinuous, are generally smaller than 10 microns in average diameter, and are generally tacky when deposited onto a collecting surface.
xe2x80x9cBonded carded webxe2x80x9d refers to webs made from staple fibers which are sent through a combing or carding unit, which breaks apart and aligns the staple fibers in the machine direction to form a generally machine direction-oriented fibrous nonwoven web. Such fibers are usually purchased in bales that are placed in a picker that separates the fibers prior to the carding unit. Once the web is formed, it then is bonded by one or more of several known bonding methods. One such bonding method is powder bonding, wherein a powdered adhesive is distributed through the web and then activated, usually by heating the web and adhesive with hot air. Another suitable bonding method is pattern bonding, wherein heated calendar rolls or ultrasonic bonding equipment are used to bond the fibers together, usually in a localized bond pattern, though the web can be bonded across its entire surface if so desired. Another suitable and well-known bonding method, particularly when using bicomponent staple fibers, is through-air bonding.
xe2x80x9cAirlayingxe2x80x9d is a well-known process by which a fibrous nonwoven layer can be formed. In the airlaying process, bundles of small fibers having typical lengths ranging from about 6 to about 19 millimeters (mm) are separated and entrained in an air supply and then deposited onto a forming screen, usually with the assistance of a vacuum supply. The randomly deposited fibers then are bonded to one another using, for example, hot air or a spray adhesive. Examples of airlaying technology can be found in U.S. Pat. Nos. 4,494,278, 5,527,171, 3,375,448 and 4,640,810.
As used herein, through-air bonding or xe2x80x9cTABxe2x80x9d means a process of bonding a nonwoven web containing adhesive polymeric component fibers, particles or the like in which air sufficiently hot to melt one of the polymers of which the fibers or particles of the web are made is forced through the web. The air velocity often is between 100 and 500 feet per minute and the dwell time may be as long as 6 seconds. The melting and resolidification of the polymer provides the bonding. Through air bonding has relatively restricted variability and since through-air bonding (TAB) requires the melting of at least one component to accomplish bonding, it is restricted to webs with two components like conjugate fibers or those which include an adhesive. In the through-air bonder, air having a temperature above the melting temperature of one component and below the melting temperature of another component is directed from a surrounding hood, through the web, and into a perforated roller supporting the web. Alternatively, the through-air bonder may be a flat arrangement wherein the air is directed vertically onto the web. The operating conditions of the two configurations are similar, the primary difference being the geometry of the web during bonding. The hot air melts the lower melting polymer component and thereby forms bonds between the filaments to integrate the web.
As used herein, the term xe2x80x9cflushablexe2x80x9d means a product suitable for disposal in sewer or septic systems that can be flushed down an ordinary water-flushing toilet with two flushes or less nine out of ten times, and that can be successfully transported through the typical municipal sewerage system or septic system piping and pumps without incident (i.e. clogging).
As used herein, the term xe2x80x9cwater dispersiblexe2x80x9d refers to structures which when placed in an aqueous environment will, with sufficient time, break apart into smaller pieces. As a result, the structure once dispersed may be more advantageously processable in recycling processes or flushable in, for example, septic and municipal sewage treatment systems. If desired, such structures may be made more water dispersible or the dispersion may be hastened by the use of agitation and/or certain triggering means. The actual amount of time will depend at least in part upon the particular end-use design criteria.
As used herein, the term xe2x80x9ccommode linerxe2x80x9d refers to a liner for the waste receptacle of a toileting device such as a bed pan, toilet training chair, potty chair, portable toilet, commode, toilet, bucket, pail, or other suitable structure for toileting use by an individual. The commode liner is used to contain bodily wastes, and prevent contact of the bodily wastes with interior surfaces of the waste receptacle.
As used herein, the term xe2x80x9cbiodegradablexe2x80x9d means that a material degrades from the action of naturally occurring microorganisms such as bacteria, fungi and algae.
As used herein, the term xe2x80x9ctissuexe2x80x9d includes not only inextensible, dispersible cellulose based tissue products, but other nonwoven webs having the described properties such as meltblown webs of PVOH fibers, for example. The manufacture of tissue grades of varying extensibility is well known and may be obtained by conventional steps such as creping or wet microcontraction as more fully described, for example, in U.S. Pat. No. 6,270,875, incorporated herein in its entirety by reference. It includes layers that may become saturated and/or allow liquid to pass through, sometimes referred to as xe2x80x9csaturation layerxe2x80x9d.
As used herein, the term xe2x80x9cwater sensitivexe2x80x9d means a structure or layer that loses integrity in contact with water as by means of breaking up or dissolving, for example, but which maintains effective strength for the desired application.
As used herein, the term xe2x80x9cwater solublexe2x80x9d means dissolves into water as a homogeneous solution.
As used herein, the term xe2x80x9cinextensiblexe2x80x9d means having machine direction stretch of less than 15% measured using the TAPPI Test Method 494 OM-88 xe2x80x9cTensile Breaking Properties of Paper and Paperboardxe2x80x9d as the test is described in U.S. Pat. No. 5,607,551, incorporated herein by reference in its entirety. The following parameters may be used: crosshead speed: 10.0 in/min (254 mm/min), full scale load: 10 lb (4,540 g.), jaw span (the distance between the jaws, sometimes referred to as the gauge length): 2.0 inches (50.8 mm), specimen width: 3 inches (76.2 mm). The testing device may be a Sintech, Model CITS-2000 (Systems Integration Technology Inc. Stoughton, Mass.xe2x80x94a division of MTS Systems Corporation, Research Triangle Park, N.C.).
As used herein xe2x80x9cjoinedxe2x80x9d includes configurations where one element is directly or indirectly attached to another element by any means including, but not limited to, adhesives, thermal bonding, sonic bonding, chemical bonding, mechanical bonding, pressure bonding, heat and pressure bonding, hydrogen bonding, fasteners, stitching, or other means known to those skilled in the art. Joined also includes elements indirectly joined together. By xe2x80x9cindirectly joinedxe2x80x9d it is meant one element is attached to a second element by one or more intermediate members. For instance, the outer layers in an ordinary plywood laminate are indirectly joined to each other by the laminate""s intermediate layers.
Tensile: As used herein, dry CD tensile strengths represent the peak load per sample width when a sample is pulled to rupture in the cross-machine direction. The sample must be dry and have been conditioned at 73.4xc2x13.6xc2x0 F., 50xc2x15% relative humidity for at least 4 hours prior to testing. Samples are prepared by cutting a 3-inch widexc3x976-inch long strip in the cross-machine direction (CD) orientation. The instrument used for measuring tensile strengths is an MTS Systems Synergie 100. The data acquisition software was MTS TestWorks(copyright) 3.10 (MTS Systems Corp., Research Triangle Park, N.C.). The load cell is selected from either a 50 Newton or 100 Newton maximum, depending on the strength of the sample being tested, such that the majority of peak load values fall between 10-90% of the load cell""s full scale value. The gauge length between jaws is 4xc2x10.04 inches. The jaws are operated using pneumatic-action and are rubber coated. The minimum grip face width is 3 inches and the approximate height of the grip face of the jaw is 1.0 inch. The crosshead speed is 10xc2x10.4 inches/min. The sample is placed in the jaws of the instrument, centered both vertically and horizontally. The test is then started and ends when the specimen breaks. The peak load is recorded as the xe2x80x9cCD dry tensile strengthxe2x80x9d of the specimen. Five (5) representative specimens are tested for each product and the arithmetic average of all five individual specimen tests is the CD tensile strength for the product.
Wet tensile strength measurements are measured in the same manner, but after the center portion of the previously conditioned sample strip has been saturated with distilled water immediately prior to loading the specimen into the tensile test equipment. Sample wetting is performed by first laying a single test strip onto a piece of blotter paper (Fiber Mark, Reliance Basis 120). A pad is then used to wet the sample strip prior to testing. The pad is a green, Scotch-Brite brand (3M) general-purpose commercial scrubbing pad. To prepare the pad for testing, a full-size pad is cut approximately 2.5 inches long by 4 inches wide. A piece of masking tape is wrapped around one of the 4-inch long edges. The taped side then becomes the xe2x80x9ctopxe2x80x9d edge of the wetting pad. To wet a tensile strip, the tester holds the top edge of the pad and dips the bottom edge in approximately 0.25 inches of distilled water located in a wetting pan. After the end of the pad has been saturated with water, the pad is then taken from the wetting pan and the excess water is removed from the pad by lightly tapping the wet edge three times across a wire mesh screen. The wet edge of the pad is then gently placed across the sample, parallel to the width of the sample, in the approximate center of the sample strip. The pad is held in place for approximately one second and then removed and placed back into the wetting pan. The wet sample is then immediately inserted into the tensile grips so the wetted area is approximately centered between the upper and lower grips. The test strip should be centered both horizontally and vertically between the grips. (It should be noted that if any of the wetted portion comes into contact with the grip faces, the specimen must be discarded and the jaws dried off before resuming testing.) The tensile test is then performed and the peak load recorded as the CD wet tensile strength of this specimen. As with the dry CD tensile test, the characterization of a product is determined by the average of five representative sample measurements.
Modulus: A measure of stiffness of a web as determined by Max Slope which is the maximum slope of the machine direction load/elongation curve for the web. The tensile tester program should be set up such that five hundred points such as P1 and P2 are taken over a two and one-half inch (63.5 mm) span of elongation. This provides a sufficient number of points to exceed essentially any practical elongation of the specimen. With a ten inch per minute (254 mm/min) crosshead speed, this translates into a point every 0.030 seconds. The program calculates slopes among these points by setting the 10th point as the initial point (for example P1), counting thirty points to the 40th point (for example, P2) and performing a linear regression on those thirty points. It stores the slope from this regression in an array. The program then counts up ten points to the 20th point (which becomes P1) and repeats the procedure again (counting thirty points to what would be the 50th point (which becomes P2), calculating that slope and also storing it in the array). This process continues for the entire elongation of the sheet. The Max Slope is then chosen as the highest value from this array. The units of Max Slope are kg per three-inch specimen width. (Strain is, of course, dimensionless since the length of elongation is divided by the length of the jaw span. This calculation is taken into account by the testing machine program.)
Hydrohead: A measure of the liquid barrier properties of a fabric is the hydrohead test. The hydrohead test determines the millibars of water pressure that the fabric will support before a predetermined amount of liquid passes through. A fabric with a higher hydrohead reading indicates it has a greater barrier to liquid penetration than a fabric with a lower hydrohead. The hydrohead test is performed according to Federal Test Standard 191A, Method 5514 except that no support was used, and the measure was taken at the first drop of penetration.
Container Flush Test
The container flush test is used to determine if the container is flushable. The test uses a toilet and a lateral plumbing system, which simulates the plumbing components upstream from a sewer main or septic tank in a home. The object of the test is to determine if the container is flushable by the toilet and passes through the plumbing system without clogging.
Materials:
1. Test container such as a commode liner
2. 0.9% Saline (300 ml per test)
3. Toilet Paper (10 standard commercial grade sheets per test)
4. 1.6 gallon standard flush toilet with a minimum ball pass diameter of 2 inches (ANSI AI12.19.2, 1973)
5. Piping system composed of four inch clear plastic piping formed into an approximately 45 foot rectangular array with {fraction (1/4)} inch per foot xe2x80x9cfallxe2x80x9d and including seven elbows (90xc2x0) forming a xe2x80x9clateral piping systemxe2x80x9d. Followed by 31 additional feet with the same xe2x80x9cfallxe2x80x9d and formed with three elbows (90xc2x0) and a U bend. In the lateral piping system the pipes wind around in a rectangular pattern similar to multiple flights in rectangular stair well. The lateral piping system is formed by a short vertical section from the toilet into a 90 degree elbow, then a four-foot run followed by a 90 degree elbow, then a 3-foot run of pipe, another 90 degree elbow, a 10 foot run, a 90-degree elbow, a 3-foot run, a 90 degree elbow, a 10-foot run, a 90 degree elbow, a 3-foot run, a 90 degree elbow, and a final 10-foot run. The remaining piping is used to direct the container to the Simulated Sewer Line apparatus discussed below. Alternative plumbing could be used after the lateral piping system.
Procedure:
1. Pour 300 ml of saline into the commode liner
2. Place 10 sheets of toilet paper into the commode liner
3. Drop filled commode liner into 1.6-gallon toilet
4. Allow approximately 10 seconds for commode liner to sink to bottom of bowl
5. Flush Toilet
6. Observe that commode liner passes through the lateral piping system and does not become clogged.
Pass Criteria:
The container or commode liner is considered flushable if the container flushes in 2 flushes or less, nine out of ten times. The container must also pass through the lateral piping system without clogging. The container need not pass through the lateral piping system in only 2 flushes, but should show continuous movement down the lateral system and eventually reach the outlet.
Container Dispersibility Test
The test is used to simulate flow conditions in a sewer line, such as those typically buried beneath a street servicing a plurality of homes. Such lines are designed to have a sewage flow rate of approximately two feet per second or greater. The object of the test is to determine the degree of container or commode liner break-up prior to reaching the sewerage treatment facility as a result of transport through the sewer lines. It is important for efficient treatment facility operation to have a dispersible container. It is estimated that a container will spend approximately 90 minutes or more in transport to a treatment facility through sewer lines. Ninety minutes is considered the minimum travel time from the home to the treatment facility.
Containers, such as commode liners, were flushed according to the Container Flush Test. The outlet of the Container Flush Test deposited the containers into a Simulated Sewer Line apparatus. The Simulated Sewer Line apparatus is meant to simulate travel through the sewer line to a sewage treatment plant. As such, a flow rate of two feet per second is present in the apparatus, and the containers remain in the tester for ninety minutes. After ninety minutes, the apparatus was drained of water through a screened outlet and the sections of the container caught on the screen recovered. These sections were then measured to determine their total mass. The container is considered dispersed if no more than about 30%, desirably no more than about 25%, and more desirably no more than about 15% of the original barrier layer mass is left.
Materials:
1. Test container such as a commode liner
2. 1.6 gallon flush toilet and lateral piping system as per the Container Flush Test
3. Simulated Sewer Line Apparatus: A circular trough having an outside diameter of about six feet, a trough width of about 6 inches maintained with a water depth of about 6 inches, and a pump to circulate the water at about 2 ft/sec.
4. Ruler
Procedure:
1. Record the initial area or mass of the test container
2. Fill Simulated Sewer Line Apparatus with water up to a depth of six inches
3. Begin circulating water in the Simulated Sewer Line Apparatus
4. Ensure the outlet of the lateral piping system will deposit the container into the Simulated Sewer Line Apparatus by use of standard plumbing components
5. Drop the container such as a commode liner into the 1.6-gallon toilet (saline and toilet tissue are included)
6. Flush toilet and observe as commode liner passes through lateral piping system into the additional plumbing and into the Simulated Sewer Line Apparatus
7. Allow the container to circulate for 90 minutes
8. Turn off the water circulation
9. Remove undissolved sections of the container that are visible or floating. Be careful not to damage the sections and keep them separate from one another to avoid sticking.
10. Drain out water thorough a screen to capture any remaining pieces
11. Remove remaining pieces of the container from the Simulated Sewer Line Apparatus
12. Unravel the container pieces (drying is optional)
13. Determine the mass of container portions collected. This can be done either by drying and weighing the pieces, or by calculating the mass based on the area of the collected pieces and the basis weight of the material. Usually, the remaining pieces of the container will be portions of the barrier layer, such as PLA, when the container is formed from the composite illustrated in FIG. 1, but can be other materials. Calculate the percent of the original container mass remaining.
14. Clean up circular transport tester